The present invention relates to a pulling cord winder for a Venetian blind, and more particularly to a pulling cord winder including a push rod with a pulling spring and a brake member to provide a compressed state and a released state to facilitate positioning the Venetian blind by pressing rough surfaces separately disposed on both sides of an arc compressing board of the brake member and using the resilience of two compressed resilient springs disposed in a winding reel accommodating space for lifting or lowering the Venetian blind.
1. Field of the Invention
In general, a Venetian blind or shade usually comes with a pulling cord or string for lifting or lowering. Since the external pulling cord is usually exposed, children may play with the pulling cord for fun, and the pulling cord may hang a child's neck or even strangle the child and cause a fatal accident. Therefore, the safety issue is taken into consideration and the pulling cords are collected under a lower rail of the Venetian blinds or shades to prevent potential risks and accidents caused by the exposed pulling cord.
2. Brief Discussion of the Related Art
U.S. Pat. No. 6,024,154 discloses a Venetian blind lifting mechanism A with concealed pulling cords as depicted in FIG. 1.
The Venetian blind lifting mechanism A is installed in the interior of a lower rail B1 and a S-shape winding member C is installed separately on both sides of a cord retrieving/winding member A1 and disposed at two corresponding coiling rods C1, C2. The coiling rod C1 at the inner side of the S-shape winding member C is pivotally coupled with a gear A11 without being engaged with the serrate rack A10, because the gear A11 has a tooth-to-tooth correspondence with the rack A10. Therefore, the gear A11 can be pulled and moved by a pulling cord C3, when the Venetian blind B is lifted or lowered. A tooth tip A110 of the gear A11 is pressed by any tooth tip A100 of the serrated rack A10 at a certain point, and such tooth tip A110 will be worn out easily (as shown in FIG. 2), and thus making it difficult to position the pulling cord C3. However, the Venetian blind lifting mechanism A of this sort usually comes with a set of complicated components and a large housing because the Venetian blind lifting mechanism A has a S-shape winding member installed separately on both sides. The size of the lower rail B1 is also increased, and thus occupying more spaces and increasing the overall cost of the assembly. Increasing the weight of the lower rail B1 exerts a larger force on a spring installed in the Venetian blind lifting mechanism A, and thus shortening the life of its use.
U.S. Pat. No. 6,575,223 B1 has disclosed another concealed type lifting control mechanism for a Venetian blind as depicted in FIG. 3. In FIG. 3, a conventional Venetian blind D has a pulling cord winder E installed at a lower rail D1, and a brake clamping board E1 of the pulling cord winder E includes a cam E2 having a latch groove E20 at a circular wheel surface and being disposed on both sides, and a pressing board E3 installed in the middle and having a latch member E4 protruded from the pressing board E3. Seemingly, the cam E2 can be latched with a latch member E4 disposed in the middle and separately protruded from the middle as shown in FIG. 4A, yet the latch member E4 is latched with the latch groove E20 of the cam E2, when a Venetian blind D is pulled or wound. The latch member E4 will slide easily due to an external force or a collision, so that the latch member E4 cannot be latched into the latch groove E20 of the cam E2, and thus the Venetian blind D cannot be pulled or wound to achieve the positioning effect (as shown in FIG. 4B.)